A. This is just a math trick - normal mortgage payment is per month, so each year you will have 12 payments. However, if you set up bi-week payments, each year you will make 13 payments, this adds up will save a lot for you.
You can use a calculator at Bankrate.com to see the total interest savings.
If you intend to set it up this way, don't pay any third party to do this for you, you can call your mortgage company and set it up by yourself, free.